Trials to inject stem cells into brains of Parkinson's patients could begin next year

Patients with Parkinson's disease could have stem cells injected into their brains to replace damage nerves and restore movement as early as next year, following successful trials in monkeys.

A team of Japanese scientists made the prediction after successfully restoring nerve cells destroyed by a similar condition in primates.

The animals, suffering an artificially induced version of the disease, showed significant improvement two years after having precursor dopamine neurons derived from human stem cells transplanted into their brains.

Charities said if the effect could be replicated in humans it would be 'a groundbreaking feat.'

The scientists say they are now just a short step away from testing the treatment, based on laboratory-made stem cells called induced pluripotent stem (iPS) cells, in clinical trials. They hope to start looking for suitable patients within the next 15 months.

The injections help restore brain function for people with Parkinson's disease

Professor Jun Takahashi, a Parkinson's neurosurgeon from Kyoto University, who led the research, said: "The monkeys became more active after cell transplantation: moved more rapidly and more smoothly, and showed more various type of movements and less tremor.

"And also they payed more attention to the outside. If I try to describe it, I would say that it is like a monkey almost sitting gets to walk around in the cage."

IPS cells are made by genetically reprogramming ordinary adult cells, often taken from connective tissue, so that they revert to an embryonic-like state.

Like stem cells extracted from early embryos, they can then be coaxed to develop into a desired cell type - in this case, dopamine neurons.

The new study involved 11 macaque monkeys displaying Parkinson's-like symptoms of tremors and impaired balance caused by a neurotoxin.

Some of the monkeys were given dopamine neuron progenitors grown from iPS stem cells derived both from human Parkinson's patients and healthy donors, but both were effective.

Brain scans confirmed that the cells were functioning as expected and not triggering a damaging immune response.

A key finding from the research, published in the journal Nature, was that no tumours had appeared in the monkey's brains - a recognised hazard of experimental stem cell therapies.

Regenerative Medicine at the University of Edinburgh, said: "This is extremely promising research demonstrating that a safe and highly effective cell therapy for Parkinson's can be produced in the lab.

"Such a therapy has the potential to reverse the symptoms of Parkinson's in patients by restoring their dopamine-producing neurons. The next stage will be to test these therapies in a first-in-human clinical trial."

David Dexter, Deputy Research Director at Parkinson’s UK added: “Both of these studies represent an important development in the field of transplantation as a potential treatment for Parkinson’s.

"Current medication only serves to mask the symptoms of the condition, but makes no changes to the brain cells themselves. These studies show that, should brain cell transplantation become a viable therapy, it has the potential to reverse Parkinson’s by replacing the dopamine cells that have been lost – a groundbreaking feat."